Czech Leader, Fearing Soviet Backlash, Says the Time Isn’t Right to Join NATO : East Europe: Havel acknowledges the danger of links with the West that exclude Moscow.

Under the looming threat of a backlash by conservatives in the Soviet Union, Czechoslovak President Vaclav Havel asked Thursday for increased support from--but not yet full membership in--the North Atlantic Treaty Organization.

Havel, becoming the first head of an Eastern European government to address NATO, acknowledged that the transformation of the former Soviet satellites into democratic societies and capitalist economies faces “more impediments than was originally expected.”

“Our countries are dangerously sliding into a certain political, economic and security vacuum,” he told delegates of the 16 NATO members. “The old, imposed political, economic and security ties have collapsed, yet new ones are developing slowly and with difficulty, if at all.”

He asked for “a lasting system” for cooperation between NATO and the former members of the Warsaw Pact, the Soviet-dominated military alliance that faced NATO from Eastern Europe until its dismantling last year. But he added that, “for a number of different reasons, our country cannot become a regular member of NATO for the time being.”

Those reasons, according to NATO officials, amount mostly to one: the danger that NATO membership for Czechoslovakia and its East European neighbors might isolate the Soviet Union and feed the fears of the conservatives who are jockeying for influence in the government of President Mikhail S. Gorbachev.

“We don’t want a NATO of 20 members and one enemy across the street called the Soviet Union,” said a NATO official who asked not to be identified.

William H. Taft IV, the U.S. ambassador to NATO, promised Havel his support. Without naming the Soviet Union, Taft said: “This dialogue and cooperation will not be directed against any other party nor aimed at isolating any nation.”

Likewise, NATO Secretary General Manfred Woerner, speaking at a joint press conference with Havel, welcomed Czechoslovakia into the new and evolving security architecture for Europe. “NATO,” he said, “will remain a pillar, if not the pillar, of a new architecture.”

In fact, NATO and the former Warsaw Pact members--the Soviet Union included--have already established a variety of formal and not-so-formal links.

Each of the Eastern nations has designated its ambassador to Belgium as, in addition, its diplomatic liaison to NATO. Treaty organization committees, particularly on politics and economics, meet frequently with representatives of some or all of the former East Bloc countries.

“The substance of the relationship is becoming richer,” said the NATO official. “The label for the relationship is not there, and we do not want it to be there under these circumstances.”

Havel cited recent developments in the Soviet Union as among the forces threatening the fragile democracies of Czechoslovakia and its East European neighbors.

“Progress toward democracy, self-determination of peoples and a working economy in the Soviet Union is being impeded by serious complications,” he said. “The conservative forces are obviously mobilizing in an effort to reverse the course of history and restore--against the will of citizens and peoples--a centralist authoritarian system.”

The most dangerous course for Eastern Europe, Havel warned, would be to forge links to the West that excluded the Soviets. That, he said, would only play into the hands of the Soviet isolationists, “who are desirous of restoring the old order of things in the Soviet Union.”

Czechoslovakia’s giant neighbor to the east is not the only threat, Havel said. Many of the region’s problems, he said, are indigenous and stem from “the general demoralization which the Communist regime has left behind.”

“Our countries are facing the threat of political and social unrest, material privations, criminal activities, increasingly intense feelings of hopelessness in society and, consequently, also the danger of populism,” he said.

Havel’s delivery, in Czech, was uninspiring. But the words of the former playwright struck many of the NATO delegates as deeply moving.

“From the time when I was young,” Havel began, “I used to hear in my country from all the official authorities, as well as from all media, one thing only about the North Atlantic alliance: that it was a bulwark of imperialism, a devil incarnate that posed a threat to peace and wanted to destroy us . . . .

“I am happy to be in a position to apologize to you today on behalf of the Czech and the Slovak peoples for all the lies which my predecessors, on behalf of the same peoples, were for years telling about you.”